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[en] ¹H NMR spectra of 2-halo-4-nitropicolines have been registered. The spectral parameters: chemical shifts as well as coupling constants have been estimated. Influence of properties of substituents on chemical shifts and coupling constants has been discussed

[en] Since ammonia, for pH control in order to minimize corrosion product in domestic PWR secondary system, is very volatile, tends to stay with steam phase, resulting in not providing proper pHs, advanced amine application is required. On the other hand, dissolved organics in the system water should be removed during purification, since they have a negative effect on cycle pH. Therefore, the characteristics of pH control agent with ammonia, morpholine, AMP, ETA and MPA were evaluated, and the effect of dissolved organics on pH and the characteristics of photocatalysis for removal of them were studied. Based on the base strength, distribution coefficient and thermal decomposition rate of them, a single amine system of MPA seems to be available. Under consideration of wet stream area protection and low temperature feedwater pH requirement, a mixed amine system of ETA with MPA or morpholines thought to be more available. The calculated values of thermodynamic equilibrium between carbonic acid, carbonate, bicarbonate and carbon dioxide agreed with the values measured from photocatalytic decomposition experiments of salicylic acid. It showed that the conductivities of the aqueous solution decreased, while pH increased even with extremely small quantities of organic acids. While, results experimentally obtained from photocatalytic decomposition of the amines above showed photocatalysis would be an available process for removal of dissolved organics. (author). 35 refs., 11 tabs., 34 figs

[en] Actinide behaviour was studied in two limiting aqueous solutions: acidic and carbonate. Cyclic voltametry was validated with well-known U redox system. SIT was used to account for I influence. Taylor's series expansions to the second order were used to account for T influence. Redox potentials of actinide couples had previously been measured in non complexing media. The above data treatments give standard values for redox potential E⁰, for the corresponding entropy ΔS⁰, enthalpy ΔH⁰ and heat capacity ΔC_p⁰ changes, and also for the corresponding excess values (i.e. the variation of these thermodynamic constants with ionic strength). This methodology was here used in carbonate media to measure the potential of the redox couple PuO₂(CO₃)₃^4-/PuO₂(CO₃)₃^5- from 5 to 70 degC and from I = 0.5 to 4.5 M in Na₂CO₃, NaClO₄ media. Experimental details and full results are given for Pu. Only final results are given for Np. Previous and/or published data for U and Am are discussed. E and ΔS variations with T or I were enough to be measured. The values obtained for the fitted SIT coefficients Δε, and for ΔS and ΔCp are similar for U, Np and Pu redox reactions. Using this analogy for Am missing data is discussed. β₃^V/β₃^VI formation constant ratio of the carbonate limiting complexes were deduced from the potential shift from complexing to non complexing media for the Actinide(VI)/Actinide(V) redox couples. β₃^V(U and Pu) and β₃^VI(Np) were finally proposed using published β3^VI(U and Pu) and β₃^V(Np). For Am, this data treatment was used to discuss the AmO₂²⁺/ AmO₂⁺ redox potential

[en] The accumulation of heavy metals and radionuclides, and the adsorption of uranium and thorium for the recovery or removal from aqueous systems using various micro-organisms and biological substances have investigated by several groups of workers. The uranium adsorbing abilities of various biopigments, microalgae and chitin, a most abundant organic resource, and its derivatives were also investigated by numerous workers. Heavy metals, radioactive substances such as actinides, chlorinated organics and other compounds have been analysed in bivalves to monitor contamination impacts on marine environments. Carell et. al. studied the environmental information preserved in the annual increments of mussel shell by means of element analyses and radioactivity by using three nuclear analytical techniques, the proton microprobe (μ-PIXE), instrumental neutron activation analysis (INAA), and alpha-track autoradiography. At this paper, the uptake of thorium from aqueous systems by a marine species which is called Ircinia Muscarum (Schmidt, 1864) has been investigated. The Ircinia Muscarum samples were collected from Kusadasi in Turkey. We studied the continuous adsorption of thorium on Ircinia Muscarum. The experimental study was carried out at the optimum conditions of thorium uptake. For these conditions at first the adsorption isotherm was formed. Since, this isotherm follows as non-linear sorption of the Langmuir model, we assumed that this phenomena can be an adsorption system. Then we investigated the thorium adsorption at different time intervals at the temperatures of 24 degC, 50 degC and 70 degC, respectively. (author)